External seminar: Thibaut Brunet
External seminar: Thibaut Brunet (Pasteur Institute, Paris)
"The unusual multicellularity of Choanoeca flexa"
Host: François Leulier
The transition to multicellularity was one of our main steps in our evolutionary history. Multicellularity is thought to have evolved more than 20 times independently across eukaryotes. Classically, multicellular development has been classified into two types: clonal multicellularity (where a mother-cell undergoes serial cell division without daughter cell separation) and aggregative multicellularity (where independently living cells converge and adhere to one another to give rise to a colony). Here, I will report on the recent discovery of a multicellular life cycle, that of the choanoflagellate Choanoeca flexa, that defies that dichotomy by combining features of clonal and aggregative development. By characterizing the life cycle of C. flexa in its natural environment, evaporating splash pools of the rocky shore of Curaçao, we show that this unusual mode of development likely represents an adaptation to ephemeral environments marked by extreme cyclical fluctuations in salinity on the order of a few days. These findings expand the possible option space for the evolution of animal multicellularity and show that the exploration of biodiversity still holds the potential to reveal fundamental new biological phenomena.
The joint expression of particular colors, morphologies, and behaviors is a common feature of adaptation, but the genetic basis for such ‘phenotypic syndromes’ remains poorly understood. In this talk I will present how we have traced the origin and rapid introgressive spread of a sexually selected syndrome in common wall lizards. By capitalizing on the adaptive introgression of the syndrome into a distantly related lineage, we were able to identify features of the developmental and genetic architecture that contribute to maintaining trait integration. I will discuss how these insights shed light on patterns of repeated evolution in Mediterranean wall lizards.
Monday, Februrary 5th